> This is a cultural problem, not a technological one.
Its about poverty. Almost none of the communities that border these rivers will have access to organised waste disposal, never mind recycling. So the trash goes into the river. Thats bad, and I suspect that its known to be bad by the people involved, but where are the alternatives?
Check out [1] for some pretty horrifying descriptions of what plastic pollution is doing to coastal communities in Cambodia. Quote: "according to Water.Org, about four million people in Cambodia still lack access to safe water, leaving them with no alternative but to buy endless bottled water, perpetuating the environmentally destructive cycle. [...] this plastic waste that all the people here live amongst is unavoidable- they are not about to feed their babies the black muddy liquid that comes out of the taps, it’s poison.”
Clearly the solution involves people not throwing plastic into the rivers, but labelling dirt-poor people in a poisoned environment as having a "cultural problem" isn't going to help.
[1] https://www.theguardian.com/world/2018/apr/25/mountains-and-...